This invention relates to a multi-piece solid golf ball comprising a solid core, a mantle, and a cover, which is improved in durability and feel.
One of the traditional requirements on golf balls is a pleasant feel when hit with clubs. A number of attempts have been made to provide a soft feel by reducing the hardness of the cover. Making the cover soft provides a soft feel at the sacrifice of distance. It is generally believed that the cover must be hard for the purpose of increasing the distance. However, a hard cover detracts from the feel especially on approach shots and putting. It is thus believed difficult in the prior art to improve both the feel and distance of golf balls.
An object of the invention is to provide a new and improved golf ball which offers a pleasant feel when hit with a variety of clubs and is improved in distance, durability, and spin.
The invention is directed to a multi-piece solid golf ball comprising a solid core, a mantle of at least one layer enclosing the solid core, and a cover of at least one layer enclosing the mantle. It has been found that improvements are made by forming the mantle relatively soft, forming the cover as a highly resilient hard layer loaded with a filler of specific shape, and optimizing the hardness distribution of the core and the inertia moment of the ball. Specifically, on driver shots, a pleasant feel is obtained, and the spin rate is reduced and the reduced spin is maintained during flight, so further distance is expected. Despite the hard cover, a very soft, pleasant feel is obtained on approach shots and putting. Additionally, the lowering of crack resistance by repetitive strikes is minimized.
The invention provides a golf ball comprising a solid core, a mantle of at least one layer enclosing the solid core, and a cover of at least one layer enclosing the mantle, wherein the mantle is formed mainly of a thermoplastic elastomer having a Shore D hardness of 30 to 52. The cover is formed of a composition comprising a thermoplastic resin as a main component and a particulate inorganic filler. The solid core has a JIS C hardness at its surface and a JIS C hardness at its center, the former being at least 10 units greater than the latter. The golf ball has an inertia moment of at least 82.5 gxc2x7cm2, and especially at least 83.0 gxc2x7cm2.
Preferably the cover composition contains 100 parts by weight of the thermoplastic resin and 11 to 45 parts by weight of the particulate inorganic filler; and the thermoplastic resin in the cover composition has a Shore D hardness of at least 60. The mantle preferably has a specific gravity of at least 0.8 and a gage of 0.2 to 5.0 mm.